split is slow. However, if you want just the first character of the string (I often do), then you can significantly speed up split by giving it the value 2 as LIMIT argument.

Benchmarked code from above (obviously on a faster machine) with 1 million iterations: 

     split: 17 wallclock secs (16.69 usr +  0.02 sys = 16.71 CPU) @ 59
+844.40/s (n=1000000)
    substr:  0 wallclock secs ( 0.74 usr +  0.00 sys =  0.74 CPU) @ 13
+51351.35/s (n=1000000)
    unpack:  1 wallclock secs ( 1.02 usr +  0.00 sys =  1.02 CPU) @ 98
+0392.16/s (n=1000000)

[download]
Benchmarking a very similar code, but instead looking for the 1st char only and giving split a ,2 limit: 
     split:  2 wallclock secs ( 1.16 usr +  0.00 sys =  1.16 CPU) @ 86
+2068.97/s (n=1000000)
    substr:  1 wallclock secs ( 0.70 usr +  0.00 sys =  0.70 CPU) @ 14
+28571.43/s (n=1000000)
    unpack:  0 wallclock secs ( 0.96 usr +  0.00 sys =  0.96 CPU) @ 10
+41666.67/s (n=1000000)

[download]
#!/usr/bin/perl -w
use strict;

use Benchmark;

use vars qw/$str/;

$str = "123456789asgdjlaskjglkajblnlbnlaqjteoijqotijwojgl;akjglkj";

timethese(shift || 1000000, {
    'unpack' => sub { my $char = getn_unpack($str, 1) },
    'substr' => sub { my $char = getn_substr($str, 1) },
    'split'  => sub { my $char = getn_split($str, 1) }
});

sub getn_unpack {
    return unpack "x" . ($_[1]-1) . "a", $_[0];
}

sub getn_substr {
    return substr $_[0], $_[1]-1, 1;
}

sub getn_split {
    return +(split //, $_[0],2)[$_[1]-1];
}

[download]

Still slower than the other solutions, but nevertheless a speedup of over 10 to an unrestricted split. See if using the LIMIT argument in split would help your code.

In reply to Re: How do I get the Nth Character of a String? by PetaMem
in thread How do I get the Nth Character of a String? by vroom

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.